We propose a two-day workshop for Spring/Summer 2015 titled Operationalizing Affective Complexity: Measurement and Applications. Affective complexity, or the experience of more than one emotion at the same time, has been a topic of recent debate in multiple areas including subjective well-being, decision making, judgment, attitude ambivalence, socio-emotional and social cognitive development and aging, social neuroscience, and health. Examples include research on the co-occurrence of feelings, blends of same and different emotion valences, flexible and dynamic appraisals of emotions and feelings, asynchrony of behavioral reactions and subjective feelings, spillover of moods, and transitions from one emotion to another. Evidence suggests that mixed emotional states develops over childhood and may be enhanced in later life. The phenomenological experience of affective complexity extends our fundamental understanding of the meaning of emotions. It raises theoretical and empirical questions about the measurement and analysis of emotional states, experiences, and episodes that consist of more than one emotion. The resolution of these issues has implications for how we assess affective experience, a topic of increasing interest in NIA-supported international surveys related to the measurement of subjective well-being. Research about affective complexity is dispersed in multiple journals. The definitions and methods used in the various subdisciplines differ. This poses challenges for researchers in emerging fields, including research on experienced well-being, decision neuroscience, and neuroeconomics, where the measurement of emotional states and their relevance for policy analysis and decision-making requires accurate assessment of affective states in real time, appropriately linked to context. Recent advances in aging research, regarding the complexity and changes in affective experience over the life course, have not been fully integrated into this discussion. The goal of this meeting is to strengthen links between these disciplines and approaches. The workshop will engage a diverse audience of up to 100 participants from a range of fields, including psychology of aging, affective science, behavioral economics, psychiatry, and demography. The workshop will consist of short talks and discussion sessions. Each day will end in a panel-led discussion designed to integrate across talks and sessions and engage audience (live and web streaming). The meeting will establish a multidisciplinary network to share information, promote cross talk, and facilitate collaboration. Recruitment for the conference will include several society newsletters, email groups and list serves as well as contacts with existing networks involving Program Committee members and confirmed speakers. This will allow broad coverage and diversity of discipline, academic rank, and conference participants. Output from the conference will include downloadable videos of the talks, white papers, special issue of a journal, special topic symposia at relevant conferences, and infrastructure for continued collaboration after the workshop.